The effects of low power density CO2 laser irradiation on graphene properties
Highlights
► Graphene structure was modified in a controlled manner by CO2laser irradiation. ► Thermal effect played an important role in CO2 laser irradiation on graphene. ► CO2 laser may enable high-efficiency and economical modification of graphene.
Introduction
Graphene [1], a two-dimensional (2D) sheet of carbon atoms arranged in a honeycomb lattice, has attracted tremendous attention and research efforts in recent years due to its exceptional transport properties, chemical stability and scalability of graphene devices to nano-dimensions [2].
Recently, it has been shown that laser irradiation can modify graphene quality and properties by reducing graphene layers [3], cleaning surface [4] and patterning [5]. However, all these reported works involve the use of either high power density lasers or expensive femtosecond laser [6], [7]. For example, Roberts et al. [7] showed that the femtosecond laser provided a relatively high accuracy in controlling the number of layers of the thinned graphene. A single-shot damage threshold in their study was identified to be as high as 3 × 1012 W/cm2. Krauss et al. [4] reported the investigations of structural modifications in single-crystal graphene due to laser irradiation at power density of 8 × 105 W/cm2. The modifications made to graphene included the removal of dopants and the gradual local decomposition of single-crystal graphene into a network of interconnected nanocrystallites. Comparing to these graphene irradiation applications using high-power-density lasers, CO2 laser can be an economical alternative for industry applications due to its wide use and low cost. However, the effects of low–power-density CO2 laser irradiation on graphene have not been investigated. In addition to the practical significance, the influence of the long-wavelength-laser irradiation on graphene properties is of fundamental science interest.
In this paper we report the investigation into the effects of CO2 laser irradiation on graphene. Specifically, we examine the interaction between long-wavelength-laser and graphene at different power densities. We attempt to show the feasibility of controlled graphene structure modification using laser with low power density.
Section snippets
Experimental setup
Samples of monolayer graphene sheets were prepared by chemical vapor deposition (CVD) on a Si substrate coated with 300 nm thick oxide. Each sample was irradiated by a CW CO2 laser for 5 min at one of the five different power densities: 2 W/cm2, 13 W/cm2, 30 W/cm2, 43 W/cm2 and 60 W/cm2, respectively. The diameter of the laser beam was 4 mm so that the whole sample could be irradiated. Irradiation was carried out under vacuum conditions (10−3 Pa) in order to avoid interactions with atmosphere. The
Results and discussion
Fig. 3a shows the Raman spectra of the pristine graphene and the graphene samples under laser irradiation of different power densities. These spectra manifest three important features: the disorder D peak, the zone-center G peak and the second-order 2D peak near 1350, 1580 and 2680 cm−1, respectively. For the pristine graphene, the disorder D peak is not obvious, which indicates its highly ordered crystalline structure [8].
Fig. 3b depicts the change in both the D peak and the 2D peak relative to
Conclusion
In summary, we have demonstrated that graphene structure can be modified by CO2 laser irradiation at low power density. Graphene experienced two processes under laser irradiation: (1) when the power density was low, crystalline graphene disassembled into nanocrystalline structure, which caused a dramatically increase of ID/IG. (2) when the power density increased past a certain threshold, hydrogenated amorphous carbon formed on the surface, which caused a slight decrease of the ID/IG and the
Acknowledgments
The authors greatly thank the funding support by China National Key Basic Research and Development Program (2011CB013000), British Royal Academy of Engineering and Tsinghua University Initiative Scientific Research Program (2010THZ0).
References (24)
- et al.
Direct imprinting of microcircuits on graphene oxides film by femtosecond laser reduction
Nano Today
(2010) - et al.
Production of few-layer graphene through liquid-phase pulsed laser exfoliation of highly ordered pyrolytic graphite
Applied Surface Science
(2012) - et al.
Quantifying ion-induced defects and Raman relaxation length in graphene
Carbon
(2010) - et al.
Chemical oxidation of multiwalled carbon nanotubes
Carbon
(2008) - et al.
Surface refinement and electronic properties of graphene layers grown on copper substrate: an XPS, UPS and EELS study
Applied Surface Science
(2011) Surface modification of diamond-like carbon films to graphene under low energy ion beam irradiation
Applied Surface Science
(2012)- et al.
Electric field effect in atomically thin carbon films
Science
(2004) - et al.
The rise of graphene
Nature Materials
(2007) - et al.
Laser Thinning for Monolayer Graphene Formation: Heat Sink and Interference Effect
ACS Nano
(2011) - et al.
Laser-induced disassembly of a graphene single crystal into a nanocrystalline network
Physical Review B
(2009)
Response of graphene to femtosecond high-intensity laser irradiation
Applied Physics Letters
Raman spectrum of graphene and graphene layers
Physical Reviews Letters
Cited by (25)
Tunning carrier concentration and Fermi-level in substrate-supported graphene monolayers: Effect of laser power
2023, Applied Surface SciencePhotoinduced rapid recovery of violet phosphorus/graphene heterojunction-based NO gas sensor
2023, Materials LettersInvestigation of micro/nano formation mechanism of porous graphene induced by CO<inf>2</inf> laser processing on polyimide film
2022, Journal of Manufacturing ProcessesCitation Excerpt :The surface material was removed with a high laser power of 4.92 W (10.3 %), and the bottom crater-like structure was subjected to hot melt expansion, thermal shock, and gas escape of the internal material, forming new spherical bulges and surface cracks with relatively small ID/IG ratios at detection points 6 (0.91) and 7 (1.03), as well as prominent 2D peaks in Fig. 5(e), which can be attributed to the violent thermal movement and photon effect, thereby leading to the long-term disorder of carbon atoms, the formation of sp2 hybrid amorphous carbon, and further the metastable sp3–C bond will be partially transformed into the steady-state sp2–C bond at high temperatures [20]. Therefore, the appropriate increment in laser power can promote the formation of hydrogenated amorphous carbon on the PI surface, bringing about a slight decrease in ID/IG [25]. To investigate the Raman characteristics of forming materials at higher temperatures, as illustrated in Fig. 5(f), three detection points in the crater radiation area were specifically chosen 8 (1.03), 9 (1.18), and 10 (1.24), and an obvious difference in ID/IG appeared.
Improved inter-device variability in graphene liquid gate sensors by laser treatment
2022, Solid-State ElectronicsLaser-assisted doping of graphene for transparent conducting electrodes
2021, Materials Chemistry and PhysicsBoosting wear properties of Inconel718 superalloy by uniform dispersing graphene nanoplatelets through laser melting deposition
2020, Journal of Alloys and CompoundsCitation Excerpt :The high temperature of the molten pool and high energy density irradiating GNPs, which will cause the C–C bond to break, and the graphene will be broken (ablated) into fragments [32]. When the laser power density continued to increase (720 W), intense thermal motion and photon effect might cause the long range disordered of carbon atom and form the sp2 hybridized amorphous carbon [33]. Due to the interface coupling mechanism between graphene and metal (Ni, Ti, etc.), that is, metal atoms are adsorbed on or replace C atoms, the D and G peaks of GNPs/IN718 composites are significantly broadened, as shown in the Fig. 3(b) [34].